A multichannel photomultiplier 100 shown in FIG. 1 is well known in the art. A conventional photomultiplier 100 includes a photocathode 103a disposed on an inner side of a light-receiving faceplate 103. Electrons are emitted from the photocathode 103a in response to incident light on the photocathode 103a. A focusing electrode 113 includes a plurality of focusing pieces 123 for focusing electrons emitted from the photocathode 103a in each of a plurality of channels. An electron multiplying section 109 includes a plurality of stages of dynodes 108 for multiplying the focused electrons for each corresponding channel. An anode 112 collects electrons multiplied in multiple stages for each channel to generate an output signal for each channel.